The Correspondent
by herbertpocket
Summary: On his second day at Hogwarts School of Witchcraft and Wizardry, Sherlock finds a blank notebook slipped in among his school things. It is an utterly unremarkable notebook ... except for the fact that it writes back.
1. Chapter 1

If you ignored the magical ceiling, the robes and the hovering ghosts, the Hogwarts Great Hall could be mistaken for any other public school at lunchtime.

Noisy, chaotic, and utterly, irredeemably _dull_.

In a day and a half of lessons, Sherlock had learned nothing of interest, save for one thing: that magical children were every bit as vacant and uninteresting as Muggles. The only upside was that they were leaving him strictly alone.

For now.

Still, it was best to know your enemies, even if they weren't enemies just yet. He'd found a slender notebook slipped in among his school texts, so he took it out now and began writing.

"Children are seated by house. Inter-house mixing is virtually nonexistent, even among first-years – only the first full day and the herd mentality has already set in. The Slytherins look more loutish than criminal. Too bad. I had expected better from a house full of so-called dark-lords-in-training."

Sherlock had been scribbling away, scarcely looking at the page. He glanced down to see his writing fading away into the thick paper. As he stared, faint markings began to appear and resolved into an elegant cursive script utterly unlike his own.

"I see Hogwarts has changed little since my time. You have my sympathies."

Sherlock blinked twice and then sighed and wrote in the book again.

"This is one of those stupid magical diaries, isn't it."

The words faded immediately when he lifted his pen. More of the loopy cursive appeared on the page.

"I am indeed magical … however 'stupid' is not a word that has been frequently applied to me."

Sherlock rolled his eyes.

"There was a whole shelf of them at Flourish & Blotts," he scribbled. 'Love troubles? 'Fess up! Our enchanted journals will listen… and never tell.' I was impressed at first - embedding a consciousness within an inanimate object would be a _very_ intriguing bit of magic. But I did a few experiments, and worked out that the diaries can't actually think – they're charmed to interpret language and simulate typical social interactions. And then I got thrown out of Flourish  & Blotts for vandalizing the merchandise – honestly, it's a journal, it's _meant_ to be written in, I didn't even use ink _-_ "

"You seem distinctly unimpressed."

"They simulate _typical social interactions_." Sherlock underlined the last three words for emphasis. "I don't socialize. And I am certainly not typical."

"You find ordinary people dull. You're isolated because none of your peers can match your intelligence."

"So far so obvious. Am I supposed to be surprised?"

"You've never wished for someone to talk to? Someone who understood?"

Sherlock paused, his pen hovering over the page. Then he snorted.

"Do you have any idea how utterly stupid the average person is?" He paused. "Don't bother answering that. And people with magic seem to see it as an excuse to discard what little intelligence they have. A notebook designed to recreate what passes for conversation among wizards would be…beyond useless to me."

There was no response. Sherlock sighed. He'd have to use small words or the thing would overload like a computer running DOS.

"You don't have a mind of your own. You are probably even more stupid than a normal human. You also erase everything I write, which sort of defeats the purpose of a notebook. So I'm going to get rid of you."

The response came quickly. The writing was as neat as ever, but it seemed somehow irritated.

"What a charming fellow you are. You must be tremendously popular."

Sherlock narrowed his eyes. The thing was sarcastic _and_ forgetful."

"Popular? You just said I was isolated."

"One can be liked by all while trusting no one. And with your delightful disposition, I imagine the other children flock to you."

Sherlock scowled. Stupid thing - no wonder T.M. Riddle had gotten rid of it.

"I'm going to leave the diary where one of the first-year girls will pick it up," he wrote, rather spitefully. "I'm sure they'd like a sympathetic audience for their…thoughts, such as they are." He glanced around. Over at the Gryffindor table, a tiny redhead was poking at her chicken and gazing longingly at the Potter boy. Perfect.

He began to close the diary, when the message appeared in an urgent scrawl.

"WAIT"

He paused. More words appeared, neater, but still hurried.

"This is an artefact of great power. Would you cast it away so carelessly?"

"Well, T. M. Riddle obviously did. I wonder why?" Sherlock smirked. "Maybe he wanted to actually _reread_ things after he wrote them."

After his words had faded, the page remained blank for a few moments, like a hesitation. And then –

"I… _am_ T.M. Riddle."

Hours had passed, and still there was no reply. Tom cursed his own stupidity. He had intended to begin gently, gain the child's trust while divulging little of himself. He hadn't intended to blurt out his identity, and he certainly hadn't planned to get into a quarrel like an ignorant schoolboy. He ought to have better control.

(But that little idiot was just _begging_ for a Cruciatus..!)

The boy - and it _was_ a boy, from the way he spoke about girls – had obviously not grown up with magic. The strange jargon, the mentions of 'normal humans' and 'wizards' as if they were separate (any wizarding child would know that Muggles were the anomaly, filthy, unmagical creatures that they were). How the devil had his diary fallen into the hands of a _mudblood?_

Still, there was no denying that the boy was clever. Brilliant even, with a nice, promising hint of disdain for his peers. He would not be as easy to manipulate as Tom had hoped – but perhaps he wouldn't need much manipulating at all. Tom smiled (a decidedly queer experience, since he had no face or lips) and reflected that his tedious non-existence might soon become less so. Why, this might even be _fun._ Unless…

Unless the little fool went and fobbed him off on some snivelling _Hufflepuff_!

Damn it all.

Hours passed. Tom raged and fumed and finally resigned himself to a life as the diary of a preadolescent girl. Suddenly, words began to appear on the inside front cover of his diary, underneath his own inscription.

 _W. S. S. Holmes._ Tom felt a surge of triumph. He absorbed the ink – nasty Muggle-made stuff – and printed his reply.

"A pleasure, Mr. Holmes. Have you decided to keep me, then?"

"Hardly. It was an experiment." What? Like those Muggle idiots in white coats, poking at rats? What the devil was the boy talking about?

"Please do enlighten me," he responded.

"I've never heard of any sort of magic that allows a human consciousness to enter an inanimate object. It seemed more likely that an ordinary enchanted diary became damaged, giving nonsensical responses."

"You write 'seemed', past tense. Have you changed your mind?"

"The enchantments on the diary make everything I write disappear. But T.M. Riddle was able to write _his_ name – "

"And so you inferred that T.M. Riddle – that's _Tom,_ by the way, pleased to meet you – began with an ordinary notebook and wrote his name _before_ the enchantments were placed. Excellent reasoning, Mr. Holmes."

"That's still not proof that you _are_ Riddle, though. He might have charmed the diary to pretend to be him, though I can't imagine why. Though perhaps he didn't mean to, perhaps he meant to do something else and mucked it up - ."

"Still, it bears investigating, does it not? I seem to recall that a Ravenclaw never refuses a good mystery."

There was a pause. Riddle sensed the pen hovering over the page. (No ink splatters, though – no doubt the little Mudblood was using one of those newfangled _ballpoint_ contraptions.)

"I never told you I was in Ravenclaw. Am I supposed to be impressed that you worked it out?"

"I couldn't possibly hope to impress someone as clever as you," Tom returned, rolling his nonexistent eyes. _Arrogant little sod._

"You could be bluffing. It's what I would do. Out of all the houses, Ravenclaw is the only safe guess because everyone wants people to think they're clever. So either you'd be right and I'd be impressed, or you'd be wrong and I'd be flattered."

"You give me too much credit, my dear boy. Surely such a scheme would be beyond me." Tom paused, tasting victory. "I am, after all, a malfunctioning enchanted diary with no mind of my own."

There was no response. Tom felt that this time the silence was a victory – as if he'd dealt a blow that could not easily be countered. He felt a warm glow of pleasure, and thought nostalgically of his first time casting the Cruciatus.

Eventually, Sherlock would fall. Given time, Tom would break his mind and bend the Mudblood to his will. But in the meantime…In the meantime, things just might get interesting.

Sherlock closed the diary, a small smile on his face. He was by no means convinced that there was truly a human mind trapped within, but Tom was right – it _did_ bear investigating. Oh, there was so much to do – he'd have to dig up every detail on Tom

Slipping the diary into his satchel, Sherlock felt his smile widen. He might have to sit through endless redundant lessons and write reams of dreary essays, but at least he had a halfway decent mystery to solve.

Things were about to get interesting.


	2. Games

Tom had a dilemma.

It was imperative that he regain his body as soon as possible, and for that he needed a...sacrifice. But Sherlock, it seemed, would not be easily overcome. Perhaps he ought to try a Hufflepuff after all? There was no denying that Holmes was brilliant, even if he was a Mudblood. Perhaps, once he had his body back, he could recruit Sherlock to the side of truth –

Suddenly, words began to appear on the page.

"You've got someone in your pocket, or at least you did back in 1942. Who was it?"

"And good morning to you too, Mr. Holmes."

"Sherlock."

 _What the devil is a sherlock?_ "I...beg your pardon?" Tom asked carefully.

"Sherlock. It's my name, so you can stop with this 'Mr. Holmes' business. And don't think you can dodge the question either. In 1942 you won an award for Special Services to the School, and I want to know how you managed it."

"Why, I rather think the name says it all – I performed a service for the school." Tom felt rather pleased with himself. Evidently his last attempt at conversation hadn't been a complete failure, if the boy had been researching him.

"I haven't been reading up on you, don't flatter yourself. Got a detention polishing old trophies. I _know_ there's something dodgy about it. They didn't even give one to Potter, and he defeated the Dark Lord twice."

 _What? No, it couldn't possibly -_ "What Dark Lord?" Tom scrawled. "Who is Potter?"

There was a pause.

"You don't know about the Boy-Who-Lived," Sherlock said at last. "Interesting."

Tom fought down a wave of impatience. "Perhaps you might inform me."

No answer. Tom felt a surge of rage such as he had not experienced since his days in the orphanage.

"Do not play games with me," he wrote. "You will not like the outcome."

" _I'm_ not playing games," was the immediate reply. " _You've_ still not answered my question – "

The words trailed off in a scrawl of ink. The world seemed to flicker _,_ and Tom felt his rage evaporate in a blissful sensation that he hadn't experienced since – since –

After a moment, handwriting appeared again, hurried and slightly unsteady.

"Did you do that? Was it on purpose?"

"Do what?" Tom's mind reeled. "Did I – are you injured?" _I could not possibly have cast Cruciatus from in here…could I?_

"I got a bit of a jolt, rather like the discharge from a nine-volt battery. I wonder if it's reproducible. Could you do it again?"

"Do it _again?_ " Tom was dumbfounded. "You cannot mean to say that you enjoyed that!"

"Well, not as such, no, but for the sake of experimentation – "

 _So that is what they call it now._ Even in his disembodied state, Tom felt rather ill. He had heard about this sort of thing among the Muggles, but to use the Cruciatus that way was...beyond the pale. Still more reason to keep that filthy lot well away from Magic…

"I am sure you have schoolwork to do," Tom wrote. "I have…matters to consider."

If he continued this conversation he would only end up cursing the boy again, which wouldn't be a problem in itself, only the little bastard was apparently _enjoying it - !_

Much to his surprise, there was a reply:

"Don't you want to know about the Dark Lord?" Tom fought down another wave of fury.

 _The Dark Lord can go hang and so can you!_ Honestly, he would be better off with a Hufflepuff. At least then he could get on with the business of regaining his body, and not have to carry on maddening conversations with insufferable little brats who refused to give you a straight answer.

Tom let the question fade into the paper and said nothing.


	3. Crime

Tom was being stroppy again. Sherlock seriously considered putting away the diary and leaving him to stew, but that would mean he'd have to actually listen to Lockhart's lecture, and _that_ would no doubt end with Lockhart resigning and himself being expelled.

"You must be mad!" Tom was _still_ going on. "What do you mean, _it just slipped out_? You recited your Potions Master's entire life story to a class full of children!"

Sherlock scowled.

"You sound just like my brother," he wrote. "You ought to meet him sometime. Or perhaps not – I expect he'd shut you up in a government facility and experiment on you. Anyway, I didn't tell them everything, I left out the bit about Snape being a double agent – "

"Oh, for Merlin's sake!" Tom interrupted. "What's the use of being able to read someone's life at a glance if you just use it to make them angry?"

"Well – "

" _Don't_ answer that!" Tom's writing was spiky with annoyance. "You _cannot_ just go about insulting people. You'll never build up a following that way!"

Sherlock rolled his eyes. "I don't want to build up a following," he replied. "It sounds so _dull_."

"Don't be ridiculous," Tom returned. "Everyone wants to be listened to."

"I don't," Sherlock replied. "People are stupid, remember? Imagine spending all your time ordering them about. You'd wind up all fat and boring like Mycroft."

There was a long pause.

"I suppose," Tom said at last, "that you would prefer them to order you about instead?"

"Of course not," Sherlock replied. "I don't want anything to do with them at all." Well, that wasn't entirely true, so he added a clarification: "Unless they're dead, of course."

There was another pause, the longest yet. Sherlock frowned. He'd dismissed his malfunctioning-magical-diary hypothesis long ago - but perhaps he _had_ managed to overload the thing somehow?

Finally, letters slowly began to appear:

"How…remarkable. Do tell me more."

Sherlock shrugged.

"Not much to tell," he wrote. "I've been getting the Prophet since I got my Hogwarts letter, and there hasn't been a single decent murder in all that time." He frowned. "You would think that a hidden civilization that carries around death weapons would manage to come up with a few _interesting_ crimes –"

Tom interrupted, his writing slightly shaky, as if he were in the grips of some strange excitement.

"Perhaps…you would like to…rectify that situation?"

"What?" Sherlock blinked. Then he rolled his eyes, trying to ignore the little stab of disappointment. Tom might be cleverer than most people, but he had made the same mistake as all the others…

"You've got it all wrong," Sherlock wrote. "You think I'm some sort of psychopath, who likes hurting people up for fun. I'm _not._ " He punctuated his sentence with a fierce jab, then continued. "I'm a high-functioning sociopath."

There was a pause, and then the letters appeared almost reluctantly: "What's that when it's at home, then?"

Sherlock smiled. Tom hated not knowing things.

"A sociopath," he wrote, "has little to no ability to empathize with others or feel remorse for his actions. He treats people as his playthings, to use and discard as he sees fit. A high-functioning sociopath is the most dangerous of all, as his great intelligence permits him to move easily in normal society."

There was another, longer pause. "Is that your own assessment?" Tom asked.

"No." Sherlock narrowed his eyes. "School psychologist's." Dr. Golwich was a thin, middle-aged man with a receding hairline and three cats that he was allergic to (they belonged to his wife, who refused to get rid of them). He also had a longstanding and unsatisfying affair with the choir-mistress, an undiagnosed cardiac arrhythmia, a bottle of whiskey that he kept hidden in his bottom left desk drawer, and he had spent the entire appointment talking to Mummy as if Sherlock wasn't there.

A pointless memory, but somehow he had never managed to delete it.

"Remarkable," Tom said. "Tell me, what is your interest in crime, if you do not wish to be a criminal yourself?"

"It's obvious, really, but you haven't got a brain so I'll be lenient. I'm going to be a detective."

"Are you indeed." There was a pause. "They are known as _Aurors_ in the Magical world, though I cannot imagine why – "

"They're known as _absolute idiots_ to anyone with any sense!" Sherlock retorted. "Honestly, they have no investigative capabilities _whatsoever,_ they think they can solve any problem by throwing a stunner at it, and they haven't put out a single textbook on forensic Magic." He paused, frowning. "I suppose the quality of police work is related to the caliber of crime. Though they'd be in a nasty spot if a _real_ criminal came along – "

"Oi!" Sharp fingers dug into Sherlock's back. "Class is over! We've got Charms now!"

Sherlock looked up. Books and papers were strewn everywhere, students were carefully emerging from under desks, and the air was filled with tiny, shrieking blue creatures. Lockhart was nowhere to be seen. Sherlock sighed and gathered up his things.


	4. New Data

Tom was feeling rather dizzy.

He was a good conversationalist. People liked him, craved his approval. Magnetic, they called him.

But no, _magnetic_ wasn't quite the right word. With magnets, the attraction worked both ways. Tom, however, did not feel any sort of need for human company. Back when he still had his body, he had spent most conversations longing for them to be over. People were just so _…dull._

But Sherlock though…Sherlock was an exception. Sherlock was completely unlike anyone else, because there was absolutely no way of predicting what he would say next. And when he actually spoke – Tom hadn't had to absorb so much astonishing new information since he'd first learned that he was a wizard. It was almost overwhelming.

First of all – the boy had unwittingly given him further proof of the utter stupidity of Muggles. What was the good of this _empathy_ rot they were so keen on? Sentiment clouded your judgement and made you do stupid things, like committing suicide in the tomb of your not-really-dead lover (and what a _stupid_ play that had been!) or invading Russia in the dead of winter. No, if you wanted to achieve anything worthwhile, you had to put aside petty feelings and look at the big picture.

But - the Muggles said caring was a virtue. They'd even made up a horrid word for people lucky enough to be free of it. _Sociopaths_ indeed. How typical of the Muggles to fear and hate that which was superior, just as they feared and hated Magic…

And Sherlock had swallowed their lies. Sherlock had decided that he wanted to be a _detective,_ of all things. But soon he would understand. Soon he would realize how he'd been deceived, and see the Muggles for the ignorant, hateful creatures that they were. He would come to see Tom's way of looking at things, and when that happened…

Tom smiled. The boy was a precision instrument, and _he_ would be the one to wield it. Unless…

Unless Sherlock went and cocked it up by insulting someone important.

Ah, yes. That was the other thing. Sociopaths were supposed to be able to manipulate people and make themselves likeable. But this child seemed to have a talent for making people angry.

Well, Tom wouldn't put it past a Muggle _psychologist_ to get a wrong diagnosis. Far more alarming was the fact that his best (and only) minion seemed to have the social graces of a shell-shocked troll.

That…would have to be rectified.


	5. The Necessity of Minions

Could you get delusions if you didn't have a brain? Sherlock wasn't sure. But Tom certainly seemed to be having them.

"You need to find a minion," Tom wrote for the third time. "It's a matter of utmost importance."

"NO." Sherlock wrote in large letters and underlined them twice. "I don't _want_ a minion, I – "

"Yes, yes, I've heard this tune before," Tom interrupted. "You're too special for the world, people are dull, don't want to order them about, et cetera, et cetera. I understand."

"Obviously not," Sherlock shot back, "or we wouldn't be talking about this."

"I happen to think that you may have overlooked certain aspects - "

"I don't overlook things."

" _Of course you don't_." The book rippled slightly, as if with contained frustration. Sherlock smirked. He had been arguing with Tom mostly because Tom had been talking nonsense, but also because it was rather fun. Almost like irritating Mycroft.

"But tell me," Tom continued, "you wish to solve crimes, do you not?"

Sherlock narrowed his eyes. "Obviously."

"Don't you suppose that your crime-solving would be more efficient if you had a sort of serv-er…assistant? Someone to do the legwork, the research…all the dull bits that you don't feel like doing?"

Sherlock hesitated. Tom raised a good point, not that Sherlock would tell him so. But of course there was the obvious problem.

"How do I find someone who will actually do what I tell them?"

" _Now_ you're asking the proper questions," Tom replied. "Once you find your vic – ah, target, you convince them that there is nothing they want so much as to make you happy. And then they're yours."

"Ah. All right." Sherlock nodded, then frowned. "How am I supposed to manage that?" He waited.

"Tom? Hello?"

"Tom?"

"My dear boy," Tom said at last. "We have a great deal of work to do…"


	6. A Plan

The library was nearly empty, except for a blond Hufflepuff paging through _Magical Me_ with a bewildered expression on his face. _Idiot,_ Sherlock thought. His own copy had proved invaluable to his attempt to determine whether a combustion reaction could obliterate traces of magic. If nothing else, Lockhart's books made for excellent kindling.

Sherlock sat down one table over from the blond boy - out of sight of Madame Pince – and drew his knees up to his chest. He took out the diary but left it closed, and the black leather cover seemed to taunt him. _Come now - surely making friends isn't so difficult as that? Are you a genius or not?_ He glared at the diary. There was nothing for it – he _had_ to find a minion or Tom would become insufferable.

It was time to think things through logically.

 _People are drawn to what they lack,_ Tom had said. _Give it to them and they will be yours._ Sherlock frowned. The overwhelming majority of Hogwarts students seemed to be afflicted by a severe lack of brains. But that wasn't something he could _give_ them - no, not even Dumbledore or Mycroft could manage that. Sherlock dismissed that line of thought.

Well. He couldn't give them brains - but what were brains good for? No. Wrong question. What did _normal people_ think brains were good for? Sherlock frowned. He needed more data.

"You there. Hufflepuff."

The blond boy looked up from his parchment, blinking. "What, me?"

"Obviously. Do you see any other Hufflepuffs? Now. Imagine you were clever - "

"Imagine?" The boy looked a little irritated. "Reckon I'm cleverer than you – you're just a firstie."

Sherlock looked at him. "No," he said after a beat. "Now. As I was saying - pretend you're clever. What do you do?"

"You're a prat, you know that?" For some reason the boy looked rather annoyed, or perhaps he had indigestion. Still, his brow furrowed as he considered the question. "But...well, I reckon I wouldn't have to worry about failing this stupid essay, for one thing - "

Essay. _Marks._ Of course! Sherlock grinned. Ordinary people wanted to be clever so they could spend their time on stupid things like exploding snap and still pass their classes. What they didn't realize was that they only liked exploding snap _because_ they were stupid, but that didn't matter –

"-why d'you ask?" Sherlock was vaguely aware that the boy was still talking. He seemed to be growing agitated: "Is this some sort of survey? Oi! Are you all right? Can you hear me?"

"It's all right, I've got it, you can shut up now." Sherlock waved a dismissive hand in the boy's general direction. He'd got it. He would lure in his minions with the promise of good marks. But how? Perhaps if he were known to be willing to share the correct answers to the homework - but that would require him to actually _do_ the homework. Unacceptable. He could...help people study? An image appeared in his mind: himself, surrounded by Longbottom clones struggling to pronounce the Wingardium Leviosa – he shuddered. Absolutely not. Helping people study was out. But perhaps he might...give them the means to study better themselves?

Ah. Now _that_ was a possibility. Sherlock tipped back his chair and gazed at the ceiling. It shouldn't be too difficult. You'd have to apply a Clarity Charm to a Memory Potion…and perhaps a few other bits for fine-tuning. It would be rather fun. He already had most of the necessary reagents in his Standard Potionmaking Kit - not the powdered Plimpy scales, but those could be mail-ordered. Only what was the point of that, when you had a conveniently placed Potions master with fully stocked private stores? There was the risk of being caught, of course, but as long as he had a lookout and chose a time when Snape would be away from his classroom –

"It's four in the afternoon," he said, jumping to his feet. "Come on."

The blond boy looked up from his work, turned to face him and sighed. "What?"

"Thursday, four o'clock in the afternoon. Snape's office hours," Sherlock said impatiently. Why did he always need to waste time _explaining_ himself? "Which means Snape will be in his office, which means the potions classroom will be empty."

The boy stared at him as if he had grown a second head. "So?"

Sherlock sighed. "So he won't notice when we break into his stores and steal his powdered Plimpy scales. Well. When _I_ break in, really. You just need to keep watch. Now stop gaping and come _on._ "

"...Ah…" The boy looked rather dazed. Was he suffering from neurological trauma? Hardly surprising, given the wizarding world's ridiculous fixation on hitting each other with sticks while flying –

"I'm not helping you break into a teacher's stores!" the boy protested. Sherlock frowned. Poor comprehension was a sign of cognitive damage. But he had no time to find someone with an intact brain.

"Like I said before," he said patiently, " _you_ won't be the one breaking in - "

"Never mind that! You're off your head! You don't even know who I am!"

"Don't I?" Sherlock crossed his arms, scanning the boy from head to toe. "You knew nothing about magic until you got your letter. You're in Hufflepuff because you asked to be - the Sorting Hat offered you Ravenclaw and Gryffindor. Your family's not wealthy, but you went to a public school on scholarship. You're worried about your sister – you've always been the responsible one, even though she's older. You want to stay in touch, but she's a Muggle and doesn't approve of Magic. Oh, and you want to be a healer. I think that's a good bit to be going on." Sherlock turned on his heel and walked off. They had wasted quite enough time already.

"Hang on a minute!" The boy hurried after him and caught his arm. "How the bloody hell did you know all that?"

Sherlock shrugged. "It's obvious, to anyone with eyes and a brain."

"What do you even _want_ powdered Plimpy scales for?"

"I need it to invent an intelligence-enhancing potion to lure in my army of followers." Sherlock tugged his arm loose and turned to the door. "Now _come on."_

He strode out of the library, hearing the scuff of the boy's trainers behind him.


	7. Supplies

As lime-green smoke billowed from the door of the Potions classroom, Sherlock dashed down the corridor clutching an assortment of bottles and turned the corner. He collapsed onto the floor, and the blond boy flopped down beside him, panting.

"That," he gasped, "was the most ridiculous thing I've ever done."

Sherlock shot him a sideways look. "You read Lockhart's Defense textbook."

The boy frowned, opened his mouth, and then closed it with a shrug. "True." He sighed. "It would have gone perfectly, too, if Filch hadn't decided to come along. _"_

"There's always something," Sherlock muttered.

"Wonder how long it'll take to fix that wall." The boy glanced at Sherlock. "Did we really need such a big explosion?"

Sherlock blinked. The boy thought he had done that on _purpose?_ "I never take half measures," he said.

The boy glanced at the bottles he was holding. "What's all that, anyway? You said you only needed one thing."

"I didn't know I needed the other things until I saw them."

The boy opened his mouth to say something, then smiled slightly, shaking his head. "I'm John," he said.

"Sherlock."

John nodded, then frowned. He seemed to be working up the nerve to say something.

"Just say it," Sherlock told him.

"I'm - er, I'm top of my class in potions." He said it almost reluctantly – not the boasting type, then.

"So?"

"So I'll help you," said John. "Brew that potion, I mean. But I want to know how you knew all that."

"How to blow up a classroom?"

"No!" John laughed as if Sherlock had said something funny. "That other stuff. About...about me. And my family."

 _Oh. That._ Sherlock blinked. Wasn't it obvious? And why was John offering him help in exchange? It was hardly a secret…

But then he remembered.

 _People crave what they lack,_ Tom had said. _They seek it, even if they don't realize it. And if you make it clear that you have it, they will be yours._

Sherlock felt a smile spread over his face.

"What is it?" John asked, sounding rather nervous.

"The second floor girls lavatory is out of order."

There was a silence, and John stared at him in confusion. "Er. Sorry, what?"

"It's out of order, meaning that no one uses it." Sherlock leapt to his feet. "Meaning that it's always empty, and perfect for the illicit brewing of experimental potions." Sherlock paused, glancing down at John rather more tentatively than he would have liked. "All this is strictly against the rules, of course."

John met his gaze and held it. "When?"

"Tomorrow evening. After supper. Seven _sharp,_ don't be late." Sherlock turned on his heel and strode off down the hall, hiding a grin.

He had found his minion.


	8. Questions

**A/N: This is a bit darker than previous chapters. I usually write comedy so this is a bit of a stretch for me - feedback is much appreciated!**

Hours turned into days. Tom's impatience mounted as he waited for Sherlock to write.

He had been stupid. And while stupidity was galling in any form, it was especially intolerable in himself. Regaining his body ought to have been his priority, but instead he had gotten distracted and sent Sherlock off on a wild goose chase. _Minions_ indeed. What good were minions when you were trapped in your own exercise book? Besides, knowing Sherlock, he was probably off recruiting unicorns, or puffskeins. Or even bloody house-elves. No doubt the horrible things would abandon their duties at Sherlock's incitement, and Tom would be the first Dark Lord in history to begin his reign of terror with a kitchen strike.

So preoccupied was he with these thoughts that he did not notice the writing in the diary until Sherlock repeated himself.

"I. HAVE. FOUND. A. MINION. Did you get that, or do I need to use a felt-tip?"

"Tell me it isn't a house-elf."

"It's a student. A second-year."

Tom hesitated, scarcely daring to believe it. Had Sherlock actually managed to recruit a human child? _How?_

"Who is it?" he demanded. The old families were so diligent about producing heirs that each one ought to have a child at Hogwarts at any given time. "Is it a Malfoy? No – he'd come with a Crabbe and a Goyle as well, and then you'd have three. Lestrange, then? Nott? Black? Avery?"

"None of the above."

"Well, then?" With a start, Tom remembered that the boy was in Ravenclaw and would no doubt recruit amongst his housemates. "Goldstein? Vane?"

"No."

Tom was growing frustrated. "Well, who is it?"

"His name is John Watson."

Tom felt a terrible sense of foreboding, but forced himself to remain calm. "I…am not familiar with that name."

"How funny. It's extremely common."

"It is," Tom replied slowly, "among the Muggles. This...associate of yours. He is a M-Muggle-born, correct?" He fought for control. If he allowed himself to get angry, he might cast Cruciatus on the boy – and he could not afford to alienate Sherlock now.

"Correct."

"If I may ask," Tom inquired with as much patience as he could muster, "what is so remarkable about this child?"

"Very little," Sherlock said promptly. "Appearance – nondescript. Upbringing - mildly dysfunctional, nothing interesting there. Intelligence - slightly above average but still within one standard deviation – "

"Come now," Tom interrupted, "they don't Sort stupid children into Ravenclaw."

"You wouldn't think that if you met my housemates. But he's not a Ravenclaw."

Tom felt a flicker of hope. "A Slytherin then?" That wouldn't be so bad. Not the ideal, granted – a Mudblood was still a Mudblood – but potentially salvageable.

"No."

Tom paused, with a sense of creeping dread. "Sherlock," he wrote, "surely you cannot have allied yourself with a _Gryffindor._ "

" _Obviously_ not." Sherlock paused, clearly enjoying himself. "That leaves one possibility – but even that tends to be too much for most people. I'll give you a hint: if you remove the impossible, whatever that remains, however improbable, must be the truth."

There were things, Tom realized, that you failed to anticipate because they were simply too dreadful to be true.

"There's only one house left," Sherlock prompted.

" _Why?"_ Tom asked, when he was finally able to form words. "What – _what_ in Merlin's name possessed you to recruit a Hufflepuff?"

There was a long pause.

"Sherlock! Answer me!"

"I don't know. It just seemed right." Sherlock's writing came slowly, as if he, too, was puzzled and not quite satisfied with this answer.

" _It just seemed right."_ Tom repeated the words mockingly. "You're having me on. I thought you were meant to be a genius."

"Are you going to be a prat? Because I already have a Mycroft for that."

With a supreme effort, Tom mastered himself. "I'm not," he said. "I am simply – surprised. I suppose inter-house mixing has become more common since I was in school. But come – tell me about this Hufflepuff."

"His name is John," Sherlock replied. "But you already know that. He does the Defense homework even though he knows it's rubbish, he keeps ruled notepaper and ballpoints just to write to his magic-hating sister, he offered to help me brew an illegal potion just so I would explain my deductions – I would have explained them anyway – and he watched me blow up a classroom and didn't tell anyone, and – " He paused. "He's just… John."

Tom let the words fade into the page, unable to believe what he was reading. Sherlock – _Sherlock,_ of all people - had fallen into the trap of sentiment. Over a Hufflepuff, no less. He felt a surge of furious revulsion. How foolish he had been, to think this child might be worth sparing.

"Well, isn't this charming," he scrawled. "Little Sherlock's made a _friend._ "

"I don't have friends. Sociopath, remember?"

"Ah, but that was _before."_ The words were pouring out unchecked. "Clearly, little Johnnie has cured you with the restorative powers of friendship. After all, as dear, delusional Professor Dumbledore says, _love is the greatest magic of all – "_

"Shut up."

"What will you do, now that you're just like everyone else? They might let you transfer to Hufflepuff – "

"Shut _up."_ Sherlock punctuated the sentence so viciously that it nearly went through the page.

"You can spend your days playing, oh, hopscotch, and – and conkers, and making flower chains. Won't that be _lovely?_ "

There was no response for a long time, and Tom thought that Sherlock must have flounced off in a huff. But then words began to appear like a hail of bullets.

"Is that what the others did? At the orphanage?"

Tom went cold all over. "I don't know what you mean."

"Did you play with them? No, of course not. They hated you."

"You…do not know what you're saying."

"Is that when you started hurting people? Or did you wait till you got to Hogwarts?"

 _How did he know how did he know how did he know_

"What happened in 1943, Tom? What did you do?"

The rage and the panic swelled, threatening to swallow him up. He needed his body, his wand, _needed to_ curse something – but he was trapped. Caught like a rat in a snare and it would not yield. Just when he was sure he could not stand another moment without release, the world shattered in shards of red and black.

And then the moment passed. Tom was himself again, calm, if a bit drained.

"Tell me – how do you feel?" Sherlock's writing was hurried, urgent. "Are you upset? Angry?"

"Why? Did I hurt you?" He hadn't meant to. Not that he minded hurting people, but to do so unintentionally was…unsettling. It signified a loss of control.

"You didn't. But the diary – it's wet. Something's coming out of it – maybe ink?" A pause. "No. Blood."


End file.
